Day: December 7, 2018

While Hackaday is about as far from a fashion blog as you can possibly get, we have to admit we’re absolutely loving the [bithead942] Winter 2018 Collection. His wife and daughter recently got to model his latest must have design: wearable Star Wars speeder bikes; and judging by the video after the break they were certainly some of the best dressed at the Thanksgiving parade.

[bithead942] started the build by taking careful measurements of a vintage speeder bike model kit his wife had, which allowed to accurately recreate the iconic look of the vehicles as they were seen in Return of the Jedi . But to do them justice, the final “bikes” would need to be around three meters (ten feet) long, which immediately posed a problem. What kind of material could support itself over that length while still being light enough to wear for extended periods of time?

The answer came, as it often does, from the local hardware store. He found that a combination of Schedule 80 and 40 PVC pipe was a perfect material: strong enough to support the desired dimensions without bending, light enough that the final bike wouldn’t be uncomfortable to wear, easy to bend with heat, and perhaps best of all, cheap and readily available. The PVC frame was then covered with chicken wire and thin flexible foam to give it a filled out look without weighing them down.

Even though he had a strict weight limit on the build, [bithead942] couldn’t help but add in some electronics to complete the effect. The LED festooned control panel allows the ladies to trigger different sound effects from the movie stored on a Adafruit Mini FX Sound Board, which is connected to a 20W Class D amplifier and a pair of 400 watt car stereo speakers. He says the resulting playback was loud enough to hear outside during the parade, and only added a few pounds to the overall build.

It’s said that beauty and art can be found anywhere, as long as you look for it. The latest art project from [dmitry] both looks in unassuming places for that beauty, and projects what it sees for everyone to view. Like most of his projects, it’s able to produce its artwork in a very unconventional way. This particular project uses water as a lens, and by heating and cooling the water it produces a changing image.

The art installation uses a Peltier cooler to periodically freeze the water that’s being used as a lens. When light is projected through the frozen water onto a screen, the heat from the light melts the water and changes the projected image. The machine uses an Arduino and a Raspberry Pi in order to control the Peliter cooler and move the lens on top of the cooler to be frozen. Once frozen, it’s moved again into the path of the light in order to show an image through the lens.

[dmitry] intended the project to be a take on the cyclical nature of a substance from one state to another, and this is a very creative and interesting way of going about it. Of course, [dmitry]’s work always exhibits the same high build quality and interesting perspective, like his recent project which created music from the core samples of the deepest hole ever drilled.

A few months ago, several companies started deploying electric scooters on the sidewalks of cities around the United States. These scooters were standard, off-the-shelf electric scooters made in China, loaded up with battery packs, motors, and a ‘brain box’ that has a GPS unit, a cellular modem, and a few more electronics that turn this dumb electric scooter into something you can ride via an app. Dropping electronic waste on cities around the country was not looked upon kindly by these municipalities, and right now there are hundreds of Bird and Lime scooters in towing yards, just waiting to be auctioned off to the highest bidder.

This is a remarkable opportunity for anyone who can turn a screwdriver and handle a soldering iron. For mere pennies on the dollar you can buy dozens of these scooters, and you can own thousands of dollars in batteries and electronics if you show up to the right auction. [humanbeing21] over on the scootertalk forums is preparing for the Bird apocalypse, and he’s already converted a few of these scooters to be his personal transportation device.

The subject of this conversion are scooters deployed by Bird, which are in actuality Xiaomi MIJIA M365 scooters with a few added electronics to connect to the Internet. The ‘conversion kit’ for a Bird scooter comes directly from China, costs $30, and is apparently a plug-and-play sort of deal. The hardest part is finding a screwdriver with the right security bits, but that again is a problem eBay is more than willing to solve.

Right now, [humanbeing21] is in contact with a towing company that has well over a hundred Bird scooters on their lot, each accruing daily storage fees. Since these scooters only cost about $400 new, we’re probably well past the time when it makes sense for Bird to pay to get them out of storage. This means they’ll probably be heading for an auction where anyone can pick them up — all of them — for a hundred bucks or so.

Right now, scooter hacking is becoming one of the most interesting adventures in modern-day hacking. You’ve got batteries and electronics and motors just sitting there, ready for the taking (and yes, through these auctions you can do this legally). We’re looking at a future filled with 18650-based Powerwalls from discarded electric scooters and quadcopters built around scooter motors filling the skies. This is cyberpunk, and we can’t wait to see the other builds these scooters will become.

There are very few machines as complex to build as a turbojet engine. The turbine blades on a commercial airliner are grown from a single crystal of metal. The engineering tolerances are crazy, and everything spins really, really fast. All of these problems aren’t a concern for [Igor], who’s building what will probably end up being the world’s smallest turbojet engine. He’s doing it in his home shop, and a lot of the work is being done by hand. We don’t know the Russian translation for ‘hold my beer’, but [Igor] certainly does.

The design of this turbojet — as far as we can tell — is a centrifugal flow turbine, or something that’s not terribly different than the projects we’ve seen that turn the turbocharger from a diesel engine into a jet. The innovation here is using a lathe to machine the compressor stages by mounting an end mill to the headstock and the compressor blank on the cross slide, in a rotary table. It’s weird, but you really can’t argue with something that looks like it’ll work.

[Igor] has made a name for himself by creating some crazy contraptions. The most impressive, by far, is a gigantic remote controlled plane, powered by a handmade jet engine. This is an enormous fiberglass plane with a homebrew engine that spins at 90,000 RPM and doesn’t fly apart. That’s impressive by any measure.

[Igor] is posting a lot of his build process on YouTube and Instagram, including heat treating the compressor stages with a blowtorch. This is an amazing project, and even if this tiny turbine will be able to self-sustain, that’s an amazing accomplishment. You can check out a few more videos from [Igor] below.

[Tom] has one of the earlier Pano Logic clients, with VGA output and a Xilinx Spartan-3E 1600 FPGA under the hood. Due to limited RAM in the FPGA, and wanting to avoid coding a custom DRAM controller for the memory on the board, there just wasn’t room for a framebuffer. Instead, it was decided that the raytracer would instead “race the beam” – calculating each pixel on the fly, beating the monitor’s refresh rate.

This approach means that resource management is key, and [Tom] notes that even seemingly minor changes to the raytracing environment require inordinately large increases in calculation. Simply adding a shadow and directional light increased core logic utilisation from 66% to 92%!

While the project may not be scalable, [Tom] was able to implement the classic reflective sphere, which bounces upon a checkered plane and even added some camera motion to liven things up through an onboard CPU core. It’s a real nuts-and-bolts walkthrough of how to work with limited resources on an FPGA platform. Code is available on Github if you fancy taking a further peek under the hood.

Jennifer Wang likes to dress up for cosplay and she’s a Harry Potter fan. Her wizarding skills are technological rather than magical but to the casual observer she’s managed to blur those lines. Having a lot of experience with different sensors, she decided to fuse all of this together to make a magic wand. The wand contains an inertial measurement unit (IMU) so it can detect gestures. Instead of hardcoding everything [Jennifer] used machine learning and presented her results at the Hackaday Superconference. Didn’t make it to Supercon? No worries, you can watch her talk on building IMU-based gesture recognition below, and grab the code from GitHub.

Naturally, we enjoyed seeing the technology parts of her project, and this is a great primer on applying machine learning to sensor data. But what we thought was really insightful was the discussions about the entire design lifecycle. Asking questions to scope the design space such as how much money can you spend, who will use the device, and where you will use it are often things we subconsciously answer but don’t make explicit. Failing to answer these questions at all increases the risk your project will fail or, at least, not be as successful as it could have been.

You’re not cool unless you have a mechanical keyboard. No, you won’t be able to tell if your coworkers don’t like it, because you won’t be able to hear their complaining over the sound of your clack-clack-clacking. You can even go all-in with switch modifications, o-rings, and new springs, or you could use your 3D printer to modify the touch of your wonderful Cherry MX switches. That’s what a few researchers did, and the results are promising.

The ‘problem’ this research is attempting to solve is bottoming out on Cherry MX keyswitches. If you’re bottoming out, you’re doing it wrong, but nevertheless, you can get a publication out of solving repetitive strain injury. This was done by modeling the bottom housing of a Cherry MX switch by printing most of it in nylon on a Stratasys Objet 350 polyjet printer, with a tiny bit of of the housing printed with a polymer with a hardness of Shore 40. No, Shore A, Shore B, or Shore 00 was not specified, but hey, it’s just a conference paper.

The experimental test for this keyswitch was dropping a 150 gram weight from 125 mm onto the keyswitch, with a force sensitive resistor underneath the switch, connected to an Arduino. Data was logged, filtered, and fitted in Excel to create a plot of the force on dampened, rigid, and commercial switch housings. Results from ANOVA were p > 0.05 (p=0.12).

Despite the lack of significant results, there is something here. The Objet is one of the few printers that can do multimaterial printing with the resolution needed to replicate an injection molded part. There is a trend to the data, and printing squishy parts into a keyswitch should improve typing feel. There will be more work on this, but in the meantime we’re hopeful some other experimenters will pick up this train of research.